Σελίδα 19At present, however, the most common way of varying the blade thrust around the azimuth is through feathering—a periodic change of the blade pitch angle 00 as
a whole. This variation of 60 with azimuth must be periodic and consequently, ...

Σελίδα 123At this point, it should be recalled that this flapping motion is geometrically
equivalent to the variation of the pitch angle of the considered blade element by
the amount, A0: - Rrësult where 3 is the flapping velocity at the appropriate azimuth ...